PROCESSING COTTONSEED MEAL A Manufacturing Method for Eliminating Toxic Qualities CARL M. LYMAN, BRYANT R. HOLLAND, AND FRED HALE Texas Agricultural Experiment Station, A. & M. College, College Station, Texas Cottonseed meal is prepared by the hydraulic method under a variety of different processing conditions including time, temperature, and moisture content. The samples are tested for toxic qualities by animal feeding tests, and the gossypol content is determined by chemical analysis. Satisfactory conditions are found for the preparation of meal in which no indication of toxic qualities can be detected by guinea pig feeding tests. This can readily be accomplished without adding chemicals. The analysis for free gossypol by a new colorimetric method proves to be a reliable means of determining whether any given sample of meal will prove toxic in animal feeding tests. The sirnplicity of the new analytical procedure makes it particularly useful in studies of this kind.
T
HE protein in cottonseed meal is of high quality, and the meal is an important livestock feed. However, in certain cases commercial cottonseed meal has limitations as a feed for swine, poultry, and rabbits. For example, it is recommended (3) that the amount of cottonseed meal fed t o hogs be limited t o 9% of the ration. This amount is always safe; but occasionally a meal may be obtained that will cause the death of some of the animals if larger amounts are fed continuously over a long time. During the processing of the seed to extract the oil, a chemical change takes place which largely destroys the toxic quality of raw cottonseed. As early as 1917 Osborne and Mendel (8) reported that the toxicity of cottonseed was progressively reduced by steaming. Withers and Carruth (14) conducted feeding tests on different batches of commercial cottonseed meal on which the processing recoids were known. They concluded that meal prepared by thorough cooking was much less toxic than meal prepared by cooking for a shorter time at a lower temperature] but that even thorough cooking, according t o the methods used a t the time, did not completely eliminate the difficulty when swine were used as test animals. A number of investigations on different methods of treating cottonseed meal t o make it nontoxic are t o be found in the literature. These include steaming or heating with water (8, I O ) , autoclaving (9,6, 9 ) , and feeding with iron salts ( 1 , 13). Methods for analysis of cottonseed meal for gossypol content have been extensively studied by Halverson and Smith ( 4 , 1 1 , 1 2 ) . Methods for processing cottonseed meal under conditions which completely destroy all toxic qualities of the meal have been studied in this laboratory and are presented here.
Figure 1.
Laboratory Equipment for Experimental Processing of Cottonseed
A thermostatic control made it possible to set the cooker a t any desired t'emperature and to reproduce exactly the temperature conditions of any given test. A meta,l thermometer well was secured t o the lid of the cooker through asbestos insulat,ion and projected almost to the bottom of the interior. This made it possible t o folloly the temperature of the charge as cooking progressed. First-quality rolled cottonseed meats were secured from a commercial oil mill. They were transported and stored under refrigeration during the short period before use. The rolled meats contained enough hulls to bring the protein content of the finished meal to approximately 43%. A charge of 700 grams of meat,s was used for each test. To thi5 an exact quantity of water was added with a spray gun, and the whole was thoroughly mixed before being put into the cooker. Because small amounts of water were lost by evaporation from the spray gun, the meats were reweighed after addition of the water, and adjustments were made to secure the desired moisture content. At the end of the cooking period, the oil LT-as pressed o a t q-ith a Carver laboratory press equipped with a cage attachment. I t is known that a cold press results in low oil extraction. The press was therefore heated each time before use, in an oven maintained a t 100" C. The pressing time M-as20 ininutm. A \47iley laboratory mill was used to grind the pressed cake. METHODS OF TESTING 9431PLES
PROCESSING, EQUIPMENT, AND PROCEDURE
The various cottonseed meal preparations were tested for toxic qualities by feeding trials with guinea pigs, and the gossypol content, both free and tot,al, vias determined by chemical means. Guinea pigs were chosen as test animals because they are particularly susceptible to the toxic principle of cottonseed ( 7 ) . The experiments of Tithers and Carruth ( 1 4 ) show that rats are less sensitive to the toxic principle of cottonseed than are certain other animals-for example, rabbits and hogs, Because of this lack of sensitivity rats are not as suitable as eit,her guinea pigs or rabbits for critical toxicity twts on cottonseed meal. I n the feeding t>estsreported here, cottonseed meal constituted 25% of the total food consumption of the animals. The percentages of the other constituents of the mixed ration were as follows: oat meal, 29; alfalfa leaf meal, 10; alfalfa stem meal, 12; wheat bran, io; butter fat, 10; yeaqt, 2; salt, 1; and c d -
The small experimental cooker for preparing the samples of cottonseed meal is shown in Figure 1. It consisted of an aluminum chamber, 7 inches inside diameter and 6 inches deep, set in a n electrically heated oil jacket and equipped with stirring arms and a device for rotating them a t approximately 45 turns per minute. Steel arms also projected from the lid into the chamber to improve the mixing of the charge. An electric heater incased in a stainless steel tube served to heat the oil jacket. To ensure that all parts of the bath would be a t the same temperature] the hot oil was circulated thi ough a channel down one end and across the bottom of the jacket; from there it flowed back around both sides of the cooker. 1 Preliminary announcement of this work was given in the Texas Agricultural Experiment Station Annual Report for 1941.
188
INDUSTRIAL AND ENGINEERING CHEMISTRY
February, 1944
TABLE I. EFFECT OF PROCESSING VARIABLES ON TOXICITY AND GOSSYPOL CONTENTOF COTTONSEED MEAL ---Guinea -Processing DataTemw. of Time of cooker cpokSample j y k e t , in.@;, Moisture C. min. added, % No. 30 31 32 33 34 35 36 50
107 107 115 115 119 115 119 122
40 80 40 80 90 80 90 90
NO. animals in group
None None None None None
7 7 8 6 4 6 8
6 7.5 7.5
7
Pig A?. gam in wt. during 20 days, grams
Feeding TestsAv. gain in wt. during 7 weeks, grams
- 78 - 20 - 58
... ... ... ...
-t44 -t64 -t83
4-117
-32 - 16
No. deaths during 7 weeks
+,i7
+ 186
6 2 4 1 2
None None None
cium carbonate, 1. To avoid the necessity of feeding green feeds, 10 mg. of vitamin C i n 0.5 ml. of water were fed t o each animal with a medicine dropper every other day. Young guinea pigs with initial weights of 260 t o 310 grams were used in these tests. Total gossypol determinations were carried out according t o the method of Smith and Halverson ( I d ) . Free gossypol was determined by the colorimetric method of Lyman, Holland, and Hale (6). Residual oil in the meal was determined by petroleum ether extractions according to the rules of the National Cottonseed Products Association.
- % GossypolTotal
Free
0.71 0.70 0.72 0.75 0.72 0.71 0.74 0.77
0.127 0.098 0.122 0.084
0.109 0.052 0.041 0.026
Residual Oil in Meal, % 7.2 5.0 5.7 5.2 5.3 4.3 4.0 5.6
189
and seventh week. When 6% water was added t o the rolled meats before cooking, none of t h e animals died during the test period. There was also no sign of ill health, but the rate of growth of t h e animals was low. Increasing t h e amount of water used in the processing to 7.5% resulted in an inrease in growth rate of more t h a n 100%.
Table I shows that the total gossypol content of the various preparations was not significantly - changed by variations in processing. On the other hand, the free gossypol content of the meal was definitely related t o the response obtained in the feeding tests. Since moisture added t o the meats before processing seemed one of the most important factors, a second series of tests was carried out t o determine how much water was necessary. All other processing factors were maintained constant, and the same batch of cottonseed was used throughout the series.
TABLE11. EFFECTOF PROCESSING COTTONSEED MEAL WITH VARIOUSAMOUNTS OF WATER
GOSSYPOL CONTENT AND TOXICITY
The results of the first series of tests are given in Table I. With the exception of sample 50, all of these preparations were made from exactly the same batch of cottonseed. Variations in the meal must, then, have been due to the processing. Figure 2 shows the processing temperature curves for the different tests. The actual temperature of the cooking meats was always somewhat below the temperature of the hot oil jacket of the cooker. For any given fixed temperature of the jacket, the temperature curve of the cooking meats was always a little lower when water was added t o the meats; gradual evaporation of water was the cause. Before the addition ,of any water, the original rolled meats used in these tests were rather dry, containing only 8.3% moisture. In every test where no water was added t o the meats before cooking, the resulting meal showed toxic qualities, the animals lost weight, and deaths occurred in each group between the third
(Temperature of cooker jacket, 122' C.; time of cooking, 90 minutes) Grams Water Added 100 G. Meats
Beginning of Cooking Period, %
wnnea Over 4-Week Period, Grams Initial Final Gain r i g 8 J ea
Free Gossypol Content of Meal, %
As Table I1 shows, when cottonseed meats were processed with enough water t o bring the total moisture content t o 14.5%, t h e resulting meal was low in free gossypol. Guinea pigs fed this meal grew at a rapid rate and showed no signs of ill health even when maintained o n the experimental diet for 2-3 months. Using seed collected from different localities, meal which gave excellent growth response with guinea pigs has been repeatedly prepared under the following conditions: (a) addition of water t o give a moisture content of not less than 14.5%, (b) 90-minute cooking period ending with the temperature of the cooked meats close t o 115' C. (239" F,). With the experimental laboratory cooker, sufficient moisture was removed during t h e cooking period so t h a t no difficulty was encountered in pressing out the oil. "Crawling" of t h e meats in the press did take place, hgwever, when attempts were made t o process meats containing 14.5Oj, moisture for less than 90 minutes, or when the final temperature of the cooked meats was below 115' C. The data in Tables I and I1 also indicate t h a t the analysis for free gossypol offers a satisfactory method of determining whether a given sample of cottonseed meal will prove toxic in feeding tests. The simplicity of the colorimetric method (6) used for these determinations makes it particularly desirable as a means of processing control. EXPERIMENTS IN A COMMERCIAL OIL MILL
0
/O
Figure 2.
PO
30
4 0 SO T I M E - M1NUT.S
122 119
70
80
90
Temperature Curves for Processing Tests
Cooker Wator Curve Jacket Added to No. Temp., * C. Meats, % 1 119 None 2 3
60
7.5 7.5
Curve No.
Cooker Jaoke: Temp., C.
4 5 6
115 115 107
'
Water Added to Meats, % None 6.0 None
The question arises as t o whether the results obtained with the experimental laboratory equipment can be obtained in a commercial oil mill. Through the cooperation of the Brenham Cotton Oil and Manufacturing Company, 15 tons of meal were prepared which contained only 0.018% free gossypol as determined by the colorimetric method. KO toxic qualities could be detected by guinea pig feeding tests, and the animals grew a t a rapid rate.
190
INDUSTRIAL AND ENGINEERING CHEMISTRY
A stack cooker 85 inches in diameter was used t o manufacture this meal. The extra moisture was added by spray a t several points in order t o obtain the best mixing possible; some was added before the rolls, some into the conveyor after leaving the rolls, and some directly into the top cooker. The moisture content was determined on samples taken as the meats were dumped from the first to the second cooker. Some variations occurred in these values, but none of the tests showed a moisture content less than 14.5%. With the aid of draft fans in the lower cookers, sufficient moisture was removed so that no difficulty MYAS encountered in the pressing operation. The cooking time was 90 minutes, and the final temperature of the meats before pressing varied between 237 and 240 F. Some of this meal was fed to hogs in a mixed ration containing 20% cottonseed meal during a test period of 90 days. The average initial weight of the animals was 52 pounds. No indication of gossypol poisoning could be detected. The test is being repeated with a ration containing 25y0 of this cottonseed meal. O
Vol. 36, No. 2
cottonseed by the hydraulic method, and t o P. 3. Lemm and C. W. Rankin of the Brenham Cotton Oil and Manufacturing Company for cooperation in the preparation of several tons of experimental meal. Since 1942 the program of research on cottonseed products a t the Texas Agricultural Experiment Station has been supported in part by a grant-in-aid from the Texas Cotton Research Committee, LITERATURE CITED
Gallup, W. D., J . Biol. Chem., 77, 437 (1928). Gallup, W. D., J . Dairy SOL,10,519 (1927). Hale, F., Texas Agr. Expt. Sta., Bull. 410 (1930). Halverson, J. O., and Smith, I?. H., IKD.ENQ.CHEM., ANAL.ED., 5, 29 (1933).
Hassel, B., Seifensieder-Ztg., 57, 52 (1930). Lyman, C. M., Holland, B. R., and Hale, F., IND. EPTG. CHEM., ANAL.ED.,15, 489 (1943).
Macy, I. G., and Mendel, L. B., J . Pharmacol., 16, 345 (1920). Osborne, T. B., and Mendel, L. B., J . Bid. Chem., 29,289 (1917). Robison, W. L., Ohio Agr. Expt. Sta., Bull. 534 (1934). Sewell, W. E., Ala. Polytech. Inst. Agr. Expt. Sta., Bull. 259 (1943).
ACKNOWLEDGMENT
The authors wish to express their appreciation to T. J. Harrell, manager of Traders Oil Mill, for generous supplies of rolled cottonseed meats, t o C. W'. McMath for valuable information in connection with practices in general use in the processing of
VITAM N A I N S STEWART SPRINGER AND PRICE M. FRENCH Shark Industries, Inc., Hialeah, Fla.
C
ONSIDERABLE interest in methods for exploiting the relatively abundant supply of sharks and rays in Florida waters has developed because of the increased demand for vitamin A. The spectacular growth of the Pacific Coast shark fishery has been given wide publicity, particularly with respect t o the high prices paid for livers of the soup-fin shark. The fact t h a t these premium prices were paid for livers consistently containing oil of exceptionally high vitamin A potency has not been emphasized by the press. The result is a widespread impression that all shark livers are of extraordinary value or that all livers of some species of sharks bring fabulous returns. Table I shows that the potencies of liver oil samples from sharks and rays of the Florida region vary f r o p 35 to 340,000 U.S.P. units of vitamin A per gram, and that individual sharks of the same species may provide oil in a wide range of potency. Although a relatively large mass of data has been collected on oil produced in South Florida over the past two years, we are unable to obtain from it any figures showing definite seasonal or locality correlations with vitamin A potency. We know of no haphazard shark fishing operation in the shore waters of Florida in which the total production of oil averages more than 8000 U.S.P. units of vitamin A per gram. However, there is an apparent increase in the ratio of the quantity of vitamin A to the amount of oil produced a t fishing stations where the attention of fishermen is directed to the importance of the vitamin rather than the oil, and where conditions permit flexibility in fishing methods. The size and species of fish forming the bulk of a catch are under the control of the fisherman, a t least to the extent t h a t these factors are influenced by the methods of handling gear and by the choice of a particular time and place for fishing. The more skillful fishermen not
Smith, F. H., IND. ENG.CHEX.,ANAL.ED.,9, 517 (1937). Smith, F.H., and Halverson, J. O., Ibid., 5 , 319 (1933). Withers, W.A., and Brewster, J. F., J . Biol. Chem., 15,
161
(1913).
Withers, W. A., and Carruth, F. E., J . Agr. Research, 14,
425
(1918).
LS
LIV
Shallow-Water Sharks and Rays of the Florida Region TABLE I.
VITAMIN
A
LIVERO I L FROM FLORIDA REGION
POTENCIES OF
RAYSOF
THE
SHARKS AND POTENCY
SPECIES Nurse shark, Ginglymostoma cirratum
No. OF LIVERS h?ATURITY 1 1
1
2 4 Many Many Many Many Tiger & leopard 1 sharks, 1 Galeocerdo 1 UrCtiCus 1 Many Many Many Bull, mullet, & 1 Salerno maok1 ere1 sharks, 1 1 Carcharinus platuodon 1 1 1 1
Black-nosed shark, Cnrcharinus acronolus Sand-bar shark, Carcharinus milberti
Many Many 1
Adult Adult Adult
SEX
Male Female Male Female ... Female ... Both Both Both ... Both Adult Female Immature Female Not detd. h-ot detd. Both Both Both Male Adult Male Adult Immature X a l e ddult Male Male Adult Male Adult adult Male Female Adult .. Both Both Adult Female
... ... ... ... ...
I
.
.
. . ..
SOURCn
Salerno, Fla. Florida Florida Florida Florida W. Coast Fla. Florida Keys E. Coast Fla. E . Coast Fla. Florida Florida Bahamas Bahamas W. Coast Fla. W. Coast Fla. W. Coast Fla. Salerno Salerno Englewood Salerno Salerno Salerno Salerno Salerno E. Coast Fla. Florida Keys Florida Keys
Male Salerno Female Salerno Female with Salerno Pups 1 Adult Female with- Salerno out pups" Salerno Many Late embryos E. Coast Many ,. Both i\lany ,.. Both E. Coast E. Coast Many ... Both &
